Surface developer with heterocyclic mercaptan for use on internal image emulsion

ABSTRACT

Processes and compositions for developing or stabilizing image records in photographic, internal image, silver halide compositions. In one aspect, the developing or stabilizing compositions of this invention contain low concentrations of a silver complexing agent. In another aspect, photographic compositions are stabilized or developed with a process comprising a bleach bath followed by a surface type developer. In a preferred embodiment direct-print materials containing either photodeveloped images or nonphotodeveloped latent images can be processed to provide permanent image records.

United States Patent Inventor Roger M. Cole Rochester, N.Y. Appl. No. 731,275 Filed May 22, 1968 Patented Oct. 26, 1971 Assignee Eastman Kodak Company Rochester, N.Y.

SURFACE DEVELOPER WITH IIETEROCYCLIC MERCAPTAN FOR USE ON INTERNAL IMAGE EMULSION 13 Claims, No Drawings U.S. Cl 96/61, 96/108, 96/63, 96/66.5 Int. Cl G03c 5/38 Field of Search 96/108, 61, 63, 66.5, 66

References Cited UNITED STATES PATENTS 3,335,009 8/1967 Rasch et al. 96/61 3,241,971 3/1966 Kitze 96/108X 3,396,017 8/1968 Baconetal. 3,418,124 12/1968 Hunt Primary Examiner-Norman G. Torchin Assistant Examiner-Won H. Louie, J r. Att0rneysW. 11.1. Kline, G. E. Battist and B. D. Wiese ABSTRACT: Processes and compositions for developing or stabilizing image records in photographic, internal image, silver halide compositions. In one aspect, the developing or stabilizing compositions of this invention contain low concentrations of a silver complexing agent. In another aspect, photographic compositions are stabilized or developed with a process comprising a bleach bath followed by a surface type developer. In a preferred embodiment direct-print materials containing either photodeveloped images or nonphotodeveloped latent images can be processed to provide permanent image records.

SURFACE DEVELOPER WITII I-IETEROCY CLIC MERCAPTAN FOR USE ON INTERNAL IMAGE EMULSION This invention relates to processes and compositions for developing or stabilizing image records in photographic materials. In one aspect this invention relates to novel processes for developing or stabilizing image records in directprint, photographic materials. In another aspect, this invention relates to novel processes comprising bleaching and then developing or stabilizing image records in direct-print -material. In still another aspect, this invention relates to a means by which both latent images and photodeveloped images can be made into stable, permanent image records.

It is often desirable to permanize (i.e., to make permanent archival quality records) the image records in printout or direct-print compositions. Many printout and direct-print compositions produce high background density when the image records are subjected to conventional developers. The increase in background fog is especially a problem when photodeveloped direct-print records are stabilized or developed in conventional developers; in this instance photolytic silver is generally formed in both the image and background areas of the record. Moreover, single developing or stabilizing compositions known in the present art generally can not be successfully used to provide good stable image properties in both nonphotodeveloped and photodeveloped direct-print compositions. Therefore, improved means to obtain good stabilized records in printout or direct-print emulsions would be desirable.

It is an object of this invention to provide new means for stabilizing or developing internal image silver halide photographic compositions.

It is another object of this invention to provide new means for stabilizing or developing direct-print and printout photographic compositions.

It is another object of this invention to provide a means for producing a uniform image in a direct-print record which has been photodeveloped over only a portion of the record area.

It is another object of this invention to provide novel compositions for developing or stabilizing photographic compositions. 7

These and other objects of the invention have been accomplished by processing internal image silver halide materials in a surface developer containing low concentrations of a selective silver complexing agent and a silver halide developing agent. The surface developer is substantially free of strong silver halide solvents such as thiocy'anates, hypo, etc. It is quite unexpected that low concentration of the selective silver complexing agents would provide improved development properties in this system since higher concentrations of the same compounds do not exhibit the same improvements in the development characteristics of the system. It is even more unexpected that this system can be used to permanize good images in both nonphotodeveloped and photodeveloped direct-print compositions.

In one embodiment, direct-print compositions which have been imagewise exposed are processed in a surface developer containing selective silver complexing agent, fixed and washed.

In another embodiment, direct-print records which have been imagewise exposed are photodeveloped to a discernible image and then processed in a surface developer containing a selective silver complexing agent, fixed and washed.

In another embodiment, direct-print compositions which have been imagewise exposed are bleached and then processed in a surface developer containing a selective silver complexing agent, fixed and washed.

In still another embodiment, direct-print compositions which have been imagewise exposed are photodeveloped, bleached, processed in a surface developer containing a selective silver complexing agent, fixed and washed.

The selective silver complexing agents of this invention contain two characteristic groups which provide the unique properties in the surface developers. The silver complexing agents contain at least one group which is capable of forming a normal covalent bond with silver. Typical complexing agents contain groups capable of forming the covalent bonds such as -S-Ag, N-Ag and the like. The preferred complexing agents contain imide groups mercaptan groups (SI-l) and the like or tautomers thereof. The complexing agents also contain at least one secondary bonding group which does not generally form a covalent bond with silver under the conditions generally encountered in photographic emulsions and photographic developing solutions. Bonds of this type are sometimes referred to as 1r bonds in the atomic configuration of the ion complex formation. Typical groups in the silver complexing agents of this invention which can be classified as'secondary bonding groups are or carbon-carbon double bond groupsythese groups can occur for example as part of a hertocyclic ring system as in 2-mercaptoimidazole or in an alkyl side chain as in l-allyl-2-thiourea, (2) aromatic substituents; typical compounds of this type are benzo or phenyl derivatives, (3) donor atoms containing 2 nonbonding electron pairs; typical preferred groups of this type are S-S and the like. I

The silver complexing agents of this invention can be additionally characterized as compounds which are soluble in water at 70F. in'concentration of at least l0' and preferably 10 moles per liter and wherein said compounds are capable of forming a silver ion complex in a ratio of at least 10 silver ion to 10 complexing agent on a molar basis in the presence of an equal molar or excess of silver ion as measured by potentiometric titration.

The silver complexing agents of this invention are incorporated in the developing solutions in lower concentrations than normally used for antifoggant purposes. In embodiments wherein the developing solution is used directly after imagewise exposure or photodevelopment it is critical to maintain the concentration level of the silver complexing agent at levels below 2X10 moles per liter of solution and preferably below 1.5Xl0 moles per liter of developing solution. The concentrations of the silver complexing agent for this embodiment are maintained between about 10 moles to about 2Xl0 moles per liter about 1X10 moles to about 1 5X10 moles per liter. In embodiments where a bleach bath is used prior to the developing bath the concentration of the silver complexing agent can be generally'from about l0" moles to about 4X10" moles and preferably from about 10" moles to not more than 2.5)(10 moles i solution. If the concentrations of the silver complexing agent exceed the above concentrations, the density of the developed image is greatly reduced.

In a preferred embodiment of this invention, direct-print compositions are stabilized ordeveloped by contacting said compositions with -a bleach bath and then contacting said compositions withthe developing solutions containing the silver complexing agentsXHowever, the bleach bath will also provide some improvements in image properties in directprint emulsions when said bleach bath is followed with other developing solutions. I

Typical compounds which can be characterized by the above tests and are effective in the developing baths of this invention are Z-mercaptothiazole, Z-mercapto benzothiazole, 2- mercapto-6-nitrobenzothiazole, 4-carboxymethyl-4- thiazoline-Z-thione, thiazolidine-Z-thione, irnidazole, 2- benzimidazoletliiol, 5-amino-Z-benzimidazolethiol, 2-mercaptoimidazole, l-methyl-2-mercaptoimidazole, Z-mercaptopyrimidine, dithiourazole, o-aminobenzenethiol, o-mercapto-benzoic acid, l-phenyl-2-mercaptotetrazole, l-phenyl-2- thiourea, S-nitrobenzimidazolethiol, 6-amino-2-mercaptobenzothiozole, 2-benzoxazolethiol, 5 -methyl-2-oxazolidinethione, 4-aminophenyldisulfide and l-allyl-2-thiourea.

ln some instances the silver halide emulsions which can be processed according to this invention contain small amounts of compounds which have the characteristics of the above silver complexing agents. This is often the case with directprint materials wherein halogen acceptors of this type are used in the compositions. However, the halogen acceptor concentration which is utilized to provide optimum image characteristics in a direct-print emulsion upon photodevelopemnt is generally too low to successfully provide the necessary image properties in a surface developer when permanizing the image record. The image record in direct-print emulsions containing these compounds as halogen acceptors are greatly improved by the use of the indicated concentrations of the silver complexing agent in the surface developer baths according to this invention.

The bleach baths which can be used in certain preferred embodiments of this invention include baths containing oxidizing agents such as, for example, those disclosed in The Journal of Photographic Science, Vol. 9, 1961, pp. 217-222. Generally the oxidizing agent concentrations of baths used in this invention is from about onegram/liter to about 100gram/liter and preferably from about 5 grams to about 50 grams per liter.

The developing bath comprises any of the conventional developing agents used for surfaces development of photographic records. Typical developing agents include hydroquinone, ascorbic acid, l-hydroxy-Z-methylaminobenzene, catechol, pyrogallol, l-phenyl-3-pyrazolidone, para-hydroxyphenyl-aminoacetic acid, t-butyl-hydroquinone, 4-methyl-4-hydroxymenthyl- 1 -phenyl-3-pyrazolidone and the like.

It is understood that the developing baths of this invention are substantially free of strong silver halide solvents or fixing agents such as water soluble thiocyanates and thiosulfates such as potassium thiocyanate and sodium thiosulfate. The presence of such strong silver halide solvents destroys the equilibrium balance necessary to obtain good results by the process of this invention.

The silver halide compositions which can be stabilized or developed according to this invention are those which are internally sensitive to electromagnetic radiation, i.e., light, X- rays, electrons, etc. Suitable silver halides include internally sensitive silver bromide, silver bromoiodide, silver chlorobromide, silver chlorobromoiodide, and the like. The preferred emulsions are those wherein the silver halide is predominately silver bromide. In a typical embodiment preferred emulsions according to this invention have higher internal sensitivity than surface sensitivity. Typical suitable emulsions are disclosed in Davey et al., U.S. Pat. No. 2,592,250 issued Apr. 8, 1952; U.S. Pat. No. 3,206,316; Porter et al., U.S. Pat. No. 3,206,313 Glafkides, Photographic Chemistry, Vol. 1, pp. 31-32, Fountain Press, London; McBride, U.S. Pat. No. 3,271,157 issued Sept. 6, 1966, McBride U.S. Pat. No. 3,287,137 issued Nov. 22, 1966, and Hunt, Photographic Science and Engineering, Vol. 5, No. 2, Mar.-Apr., l96l, pp. 104-108.

The so-called "internal image emulsions can be used in the invention, such having silver halide grains wherein a predominant amount of the sensitivity is internal to the grains. Such internal image emulsions are those which, when measured according to normal photographic techniques by coating a test portion of the emulsion on a transparent support, exposing to a light intensity scale having a fixed time between 1X10" and 10 second, bleaching 5 minutes in a 0.3 percent potassium ferricyanide solution at 65 F., and then developing in Developer Z below (an "intemal-type developer), have a sensitivity measured at a density of 0.1 above fog, greater than the sensitivity of an identical test portion which has been exposed in the same way and developed for 6 minutes at 68 F. in Developer X below (a surface-type" developer).

Water to make 1 liter The direct-print emulsions which can be stabilized in accordance with this invention generally contain halogen acceptors, for example, nitrogen containing halogen acceptors such as those disclosed in McBride, U.S. Pat. No. 3,287,137 and McBride, U.S. Pat. No. 3,271,157.

In certain preferred emulsions to be stabilized or developed by the methods of this invention, it is desirable to add watersoluble halides to the silver halide emulsion after its precipitation but before it is coated. More generally, about 1 to about 50 mole percent, and preferably about 1 to about 10 mole percent of water soluble halide based on the silver halide in the emulsion is used.

The stabilizing or developing baths of this invention can also be used to treat other silver halide systems, such as developing out system, etc., if desired to maintain or improve image proparties in said systems.

Various colloids can be used as vehicles or binding agents in preparing the silver halide emulsions of this invention. Satisfactory colloids which can be used for this purpose include any of the hydrophilic colloids generally employed in the photographic field including, for example, gelatin, colloidal albumin, polysaccharides, cellulose derivatives, synthetic resins such as polyvinyl compounds, including polyvinyl alcohol derivatives, acrylamide polymers and the like. In addition to the above hydrophilic colloids, the vehicle or binding agent can also contain hydrophobic colloids such as dispersed polymerized vinyl compounds, particularly those which increase the dimensional stability of photographic materials. Suitable compounds of this type include water-soluble polymers of alkyl acrylates or methacrylates, acrylic acid, sulfoalkyl acrylates or methacrylates, and the like.

The above-described emulsions of the invention can be coated on a wide variety of supports in accordance with usual practice. Typical supports for photographic elements of the invention include glass, metal, paper, polyolefin-coated paper, cellulose nitrate film, cellulose acetate film, polystyrene film,

polyester films such as polyethylene terephthalate film, heat resistant polymeric films such as high temperature polyester, polyimide, polycarbonate films, and the like.

The essential ingredients of the stabilizing compositions according to the invention, namely the developing agents, the selective silver complexing agent and in some embodiments,

the bleach, can be prepackaged in a kit, diluted, concentrated, or in powder form and can be either mixed together or packaged individually for use in the systems of this invention. The respective compositions are generally prepackaged in- EXAMPLE 2 Samples of direct-print silver. halide emulsions prepared according to example I] of Kitze, Belgian Pat. No. 689,515 issued Jan. [3, i967, are imagewise exposed to a step tablet on dividually and can be readily added to aqueous alkaline solu- 5 a sensitometer b ex f l0 tion or water to from th necessary baths. Therefore it is unxenon Ii ht i mg 9 to a derstood that kits prepared for making stabilizing composiphotodeveglo b ex gq z es s subsequently tions comprising the essential ingredients of this invention are illumination g 2 L d f i efci'of fluorescent contemplated to be within the scope of-this invention. th b k ens"), o t e area and r 0 e ac ground area are shown ln-table l. The invention can be further illustrated by the following ex- 0 f am lcs 0 the p isamples is processed as a con- P trol sample in Developer B for 60 seconds, then stopped for 10 seconds, fixed for 5 minutes and washed for 5 minutes. The ima e record EXAMPLE 1 g densities obtained for this pro are shown m 2 L-.. Strips of a direct-print silver halide emulsion prepared according to example Id of McBride US. Pat. No. 3,287,l36 are DEVELOPER B imagewise exposed to a step tablet on a sensitometer by exposing for 10'' second to a high intensity Xenon light. The respec- 1 tive samples are subsequently photodeveloped by exposing to r i 8-" 250 foot-candles of daylight fluorescent illumination for g ming: 3" seconds to produce a negative image with about 0.4 density Sodium carbonate so discrimination Potassium bromide 2 One of the samples is processed in Developer A., described below, for 60 seconds, then stopped in acetic acid for l0 seconds, fixed for 2 minutes in sodium thiosulfate solution and Several additional'nonphotodeveloped and photodeveloped washed for 5 minutes in running water. samples are processes in Developer B containingvthe concen- A second sample is processed by the above procedure trations of selective silver complexing agents indicated in table wherein Developer A additionally contains 0.1 g./l. ofl -phenl. The densities of the image area obtained upon development yl-S-mercaptoterazole. 30 are recorded in table I.

TABLE I Non-phtdvlpd Phtdvlpd Concendensity density tration, Y Y Developer Silver complexing agent g.ll. Bkgrnd Image Bkgrnd Image None None 0.38 o. 68 None 0.14 1. 24 0.56 0.411 D 2-mereaptoimldazole 0.1 0.12 L18 0. 52 0.85 Dodo 0.01 D0. 2-thiouraciL 0. 1 0. l4 1. 21 0. 64 0, 111 Do. .do. 0. 01 0.15 1. 21 0. as n. 64 Do FQP i 3; i3 2 8; $5 3 D0 Dlthiwmole 0% 3: l3 i133 8:33 8:23 0.1 0.16 1. 22 0. 62 0. so ZMm-mmma Z-thiwwm acid 0911i 3153 {3% 3123 3:43 z am 3313 i 31 3 22 32?,

DEVELOPER A The above data demonstrates that good image densities can be obtained with either photodeveloped or I I nonphotodeveloped direct-print samples which are processed I '"1"" 6 with surface developers containing low concentrations of Sodium lsoascorbale 40 g- Potassium bromide l g. sllver comp|exu1g n Kodulk 40 8- 4 methyl-l-phenyl-3-pyrosolidone l g. When the Z-mercaptormrdazole as used in the developer is will" "take I replaced with imidazole, l-allyl-2-thiorea or o-mercaptobenzoic acid similar improvements in photographic properties are obtained. Background Image Sample Density Density 1 Developer A 0.48 0.46 A Develo er A l-phenyl- EXAMPLE 3 S-mercaplotetrazole 0.67 l.0l

A bleach bath is preferably used when processing a directprint emulsion prior to processing in the developer containing selective silver complexing agents.

A direct-print silver halide emulsion prepared according to example 111 of McBride US. Pat. No. 3,287,136 is imagewise exposed on a .sensitometer using a 10 second flash with a high intensity Xenon lamp. The sample is then photodevelQPed by exposing it to 250 loot-candles of daylight =fluorescent illumination for 2 minutes.

A control sample is processed in Developer A for 2 minutes, Sodium Sfllfiw 500 fixcd for 5 minutes and washed in running water. A second odlum carbonate 80.0 g. sample of the above emulsion IS processed in Developer C acpomsium bmmidc 2,0 I cording to the same processing procedure. Z-mercaptoimidazole 0| 8.

5 Water to l liter DEVELOPER C A photodeveloped sample is prepared as above and then Water 800 ml bathed in an oxidizing bath (Bleach B) for l minute, then -"1= x -P l 6 8- l0 Processed in an identical manner as the control. The density l data obtained is shown in Table III. Potassium bromide l g. Kodak Balanced Alkali 40 s- 4-methyl-phenyl-S-pyrazolidone l-g. BLEACH B l-phenyl-5-mercaptotetrazole 0.l g. water to make 1 liter Potassium dichromale 20 g.

H=10 0 Sulfuric acid (cone) 4 ml.

Water to l liter Additional samples prepared by the above procedure are TABLE 1 treated with an oxidizing bath, Bleach A, for 2 minutes, then processed in a manner similar to the control sample.

Transmission Densities BLEACH A Bleach Dev Background Image None D 0.72 l.l2 Potassium dichromate 7.5 g. None E 065 L22 Sulfuric acid (cone) 5.0 ml. B D 0.l2 0.22 Water to l liter B E 0.25 0.66

The combination of the bleach bath and the developer con- The normal surface developer produced a negative image taining the selective silver complexing agents produces lower with high background density; while the bleach process folminimum density with better image discrimination than the lowed by the developer containing the selective silver comdeveloper containing the selective silver complexing agents plexing agent greatly reduced the background and maintained alone or the bleach followed b the conventional surface equivalent image discrimination. The resulting image developer. produced by the bleach process followed by the developer containing the selective silver complexing agent provides :1 TABLE ll record which is much more discernible to the eye as the image density is on a percentage basis much darker than the A background density. Similar results are obtained when l-allyl- Reflection Densitifi 2-thiourea, imidazole, dithiourazole, and l-phenyl-Z-thiourea Backgmmd are utilized in Developer E in place of the Z-mcrcaptoimidazole. None A 0.55 0.48 None c 0.51 0.09 EXAMPLE 5 A A 0.47 0.30 A C A control direct-print emulsion is prepared according to example Ia of Kitze, Belgian Pat. No. 689.515, issued Jan. l3. Examplglt I967. Another sample (sample A) ofa similar emulsion is prepared by the same procedure with the addition of Samples of direct-print silver halide emulsions prepare l5g./mole of silver of Z-mercaptoimidazole incorporated in ng l0 example 4 0f KaTlSOn, gi 705.036 the emulsion coating. Samples of the respective coatings are sued Nov. I4, 1967 (which containsa urazole halogen accepexposed for l0 second to a high intensity Xenon lamp tor) are imagewise exposed to a step tablet on a sensitometer through a 0 to 3.0 neutral density step tablet on a sensitomeby exposing for 10" second with a high intensity Xenon light. ter. The images are then photodeveloped with 245 foot-can- The respective samples are subsequently photodeveloped by dles of daylight fluorescent light for 30 seconds. The respecexposing to 50 foot-candles of daylight fluorescent illuminative photodeveloped samples are solution processed at 70 F. tion for 5 minutes. One of the photodeveloped samples is in the following solutions as indicated in table IV. processed as a control sample in Developer D for l minute, fixed for 30 seconds and washed in running water. Another Bleach A 30 seconds sample is processed for the same duration in Developer E.

Potassium dichromale 20 gJl. DEVELOPER D Sulfuric Acid (cone) 4 l.

Nmethyl-para-amlnophenul 4.5 g. DEVELOPER F mamas Sodium sulfite 50.0 g. Hydroquinnne 9.0 g. I Sodium carbonate 80.0 g. yl'p p 8 Potassium bromide 2.0 g. Hydwqumonc sw m I m" Sodium sulfite 45.0 g. Sodium carbonate 80.0 g.

Potassium romide I!) g Water to l liter DEVELOPER E Sodium thiosull'ute l40.0 60 seconds Sodium sulfite I50 g. Nmeih lurll-amino henol 4.5 g. Water In 1 liter Wash Running Water 2 minutes Additional samples are processed by the above procedure except Developer G was substituted for Developer F on the procedure. Developer G is identical in all respects to Developer F with the addition of 0.075 g./l. of Z-mercaptoimidazole.

The densities obtained in the respective photographic samples are reported in table lV below.

The selective silver complexing agent utilized in the emulsion shows an improvement in discrimination over the process without agent present. Moreover, the addition of the selective silver complexing agent in the developer in addition to the use of the same or a similar compound in the emulsion coating shows an additional improvement in the image discrimination obtained after processing.

The invention has been described in considerable detail with reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and in the appended claims.

I claim:

1. A process for developing and stabilizing image records in an internal image silver halide compositions which has been imagewise exposed comprising contacting said silver halide composition with a surface developingsolution, said solution comprising a developing agent and from moles/liter to about 2X10 moles/liter of a silver complexing agent, said complexing agent containing at least one group capable of forming covalent bonds with silver said group selected from mercaptan groups, imide groups, or tautometers thereof and at least one secondary bonding group capable of forming pibonds, said secondary bonding group consisting of I l 1 i groups.

2. A process according to claim 1 wherein said groups capable of forming covalent bonds with silver consist of mercaptan groups.

3. A process according to claim 2 wherein said silver complexing agent is 2-mercaptoimidaz'ole.

4. A process according to claim I wherein said silver complexing agent is selected from the group consisting of 2-mercaptothiazole, Z-mercapto benzothiazole, 2-mercapto-6- nitrobenzothiazole, 4-carboxymethyl-4-thiazoline-2-thione, thiazolidine-Z-thione, imidazole, 2-benzimidazolethiol, 5- amino-2-benzimidazolethiol, Z-mercaptoimidazole, l-methyl- Z-mercaptoimidazole, 2-mercaptcpyrimidine, dithiourazole,

o-aminobenzenethiol, o-mercaptobenzoic acid, l-phenyl-2- mercaptotetrazole, l-phenyl-2thiourea, 5- nitrobenzimidazolethiol, 6-amino-Z-mercaptobenzothiozole, 2-benzoxolethiol, 5-methyl-2-oxazolidinethione, 4- aminophenyl-disulfide and l-allyl-2-thiourea.

5. A process according to claim 4 wherein said silver complexing agent is selected for the group consisting of l-allyl-2- thiourea, Z-mercaptoimidazole, dithiourazole, and l-phenyl- Smercaptotetrazole. 3

6; A process according to claim 4 wherein said silver complexing agent is 2-mercaptoimidazole, in a concentration of from lXlO to about l.5 l0 moles/liter.

7. A process for stabilizing image records in light developable internal image silver halide compositions which have been imagewise exposed and photodeveloped to produce a visible image therein, said process comprising (1) contacting said silver halide composition with a silver halide bleaching solution, and then (2) contacting said silver halide with a surface developing solution comprising a developing agent and from about l0 to about 4X10 moles/liter of a silver complexing agent comprising at least one group capable of forming covalent bonds with silver, said groups selected from mercaptan groups, imide groups, or tautomers thereof and at least one secondary bonding group capable of forming pi-bonds, said secondary bonding group consisting of groups.

8. A process according to claim 7 wherein said silver complexing agent is selected from a group consisting of 2-mercaptothiazole, Z-mercapto benzothiazole, 2-mercapto-6- nitrobenzthiazole, 4-carboxymcthyl-4-thiazoline-2-thione, thiazolidine-Z-thione, imidazole, 2-benzimidazolethiol, 5- amino-2benzimidasolethiol, 2-mercaptoimidazole, l-methyl- 2-mercaptoimidazole, Z-mercaptopyrimidine, dithiourazole, o-aminobenzenethiol, o-mercaptobenzoic acid, l-phenyl-2- mercaptotetrazole, l-phenyl-Z-thiourea, 5 nitrobenzimidazolethiol, o-amino-2-mercaptobenzothiozole, 2-benzoxazolethiol, 5-methyl-2-oxazolinethione, 4- aminophenyl-disulfide and l-allyl- 2-thiourea.

9. A process according to claim 7 wherein said silver complexing agent is selected from the group consisting of l-allyl- 2thiourea, Zmercaptoimidazole, dithiourazole, and l-phenyl- S-mercaptotetrazole.

10. A process according to claim 7 wherein said bleaching solution comprises potassium dichromate, and said silver complexing agent comprises Z-mercaptoimidazole.

11. A process according to claim 7 wherein said groups capable of forming covalent bonds with silver consists of mercaptan groups.

12. A process according to claim 7 wherein said silver complexing agent is Z-mercaptoimidazole.

13. A process according to claim 7 wherein said silver complexing agent is compound which is soluble in water in a concentration of at least 10" moles/liter at 70 F. and wherein said compound is capable of forming a silver complex having a ratio of at least 1 silver ion to 1 silver complexing agent in a molar basis in the presence of excess silver ions as measured by potentiometn'c titration.

* t t i gggr UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 5,5 1 Dated October 26, 'l 971 Inventor(s) Roger M. Cole It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column line 60, after the word "containing" please insert -a--. Column 2, line 28, "hertooyclic" should read heterooyolic--; line L D, "10 should read 1 O line In, 10 should read ---|o line a2, "10" should read line L3,}, "10" should read 1 line 52,

"2X1 0 should read ZXI O line 53, "1 .5xlO should read l .5211 O line 55, "1 0 should read O line 56, "2X1 0 should read 2Xl O line 56, after "liter" insert the words and preferably from---; line 56,

"1 X1 0 should read 1 X1 O f line 57, "1 .5X1O13" should read -1 .Sxl O line 59, "1 O should read 1 O line 60, after "moles" please insert per liter-; line 60,

"hxl 0 should read Lpcl O' line 60, "10 should read O)+---; line 61 "2.5261 0 should read -2.5x| O line 61 "10" should read per liter- Column 3, line 19,

" photodevelopemnt" should read -photodevel0pment; line 36, "comprises" should read can comprise-. Column L line 1 'lxi 0 should read 1 x! O line 2, "10" should read --i line hl "1 should read --.I line 61 "watersoluble" should read waterinsoluble--. Column 5, line 6,

"from" should read --form---; line 19, "10 should read ---i O""'--; line 30, "meroaptoterazole" should read mercapi;otetrazole-; line 56, "pyrosolidone" should read pyrozolidone; line 63, "O.) B" should be listed directly under the heading; Baokground Density-; line 67, "mercaptotetraazole" should read -meroaptotetrazole---.

Page of 2. L. .J

P040510 UNITED STATES PATENT OFFICE (5 6g) CERTIFICATE OF CORRECTION Patent No 3: 1 Dated October 26 1 97 PAGE 2 Inventor(s) Roger M. Cole It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 6, line 2, "Example 11 should read --Example 1 a---; line 5, "1 0 4-" should read O line 72, "10 should read O Column 7, line 13, "1 should be inserted n 1 belmeeilL mgghg l pge y llne 55, 10 should read --I 0 --;/line 58, table" should read -Table-; line 73, 1L 0.0g" should read -2J 0.0g-. Claim 1 line 5, "10 should read O line 6, "2x1 0 should read --2x| O Claim 6, line 3, "1X1O1LL" should read --I XI O line 3, *1 .5X1O1 should read 1 .Sxi 0 Claim 7, line 8, "10 should read --l O line 8, "M610 should read. ---l xl O Claim 9, line 3, should be inserted between -2 thiourea-; line 3, should be inserted between -2 meroaptoimidazole--; Claim 1 3, line 3, "10 should read "-10- Column 3. line 2.2,

"record" should read --reoords---.

Page 2 of 2.

Signed and sealed this 9th day of May 1972.

(SEAL) Attest: EDWARD M.FLE'ICHER,JR. ROBERT GOTTSCHALK J Attesting Officer Commissioner of Patents 

2. A process according to claim 1 wherein said groups capable of forming covalent bonds with silver consist of mercaptan groups.
 3. A process according to claim 2 wherein said silver complexing agent is 2-mercaptoimidazole.
 4. A process according to claim 1 wherein said silver complexing agent is selected from the group consisting of 2-mercaptothiazole, 2-mercapto benzothiazole, 2-mercapto-6-nitrobenzothiazole, 4-carboxymethyl-4-thiazoline-2-thione, thiazolidine-2-thione, imidazole, 2-benzimidazolethiol, 5-amino-2-benzimidazolethiol, 2-mercaptoimidazole, 1-methyl-2-mercaptoimidazole, 2-mercaptopyrimidine, dithiourazole, o-aminobenzenethiol, o-mercaptobenzoic acid, 1-phenyl-2-mercaptotetrazole, 1-phenyl-2-thiourea, 5-nitrobenzimidazolethiol, 6-amino-2-mercaptobenzothiozole, 2-benzoxazolethiol, 5-methyl-2-oxazolidinethione, 4-Aminophenyl-disulfide and 1-allyl-2-thiourea.
 5. A process according to claim 4 wherein said silver complexing agent is selected for the group consisting of 1-allyl-2-thiourea, 2-mercaptoimidazole, dithiourazole, and 1-phenyl-5mercaptotetrazole.
 6. A process according to claim 4 wherein said silver complexing agent is 2-mercaptoimidazole, in a concentration of from 1 X 10 4 to about 1.5 X 10 3 moles/liter.
 7. A process for stabilizing image records in light developable internal image silver halide compositions which have been imagewise exposed and photodeveloped to produce a visible image therein, said process comprising (1) contacting said silver halide composition with a silver halide bleaching solution, and then (2) contacting said silver halide with a surface developing solution comprising a developing agent and from about 10 5 to about 4 X 10 3 moles/liter of a silver complexing agent comprising at least one group capable of forming covalent bonds with silver, said groups selected from mercaptan groups, imide groups, or tautomers thereof and at least one secondary bonding group capable of forming pi-bonds, said secondary bonding group consisting of groups.
 8. A process according to claim 7 wherein said silver complexing agent is selected from a group consisting of 2-mercaptothiazole, 2-mercapto benzothiazole, 2-mercapto-6-nitrobenzthiazole, 4-carboxymethyl-4-thiazoline-2-thione, thiazolidine-2-thione, imidazole, 2-benzimidazolethiol, 5-amino-2benzimidasolethiol, 2-mercaptoimidazole, 1-methyl-2-mercaptoimidazole, 2-mercaptopyrimidine, dithiourazole, o-aminobenzenethiol, o-mercaptobenzoic acid, 1-phenyl-2-mercaptotetrazole, 1-phenyl-2-thiourea, 5-nitrobenzimidazolethiol, 6-amino-2-mercaptobenzothiozole, 2-benzoxazolethiol, 5-methyl-2-oxazolidinethione, 4-aminophenyl-disulfide and 1-allyl- 2-thiourea.
 9. A process according to claim 7 wherein said silver complexing agent is selected from the group consisting of 1-allyl-2thiourea, 2mercaptoimidazole, dithiourazole, and 1-phenyl-5-mercaptotetrazole.
 10. A process according to claim 7 wherein said bleaching solution comprises potassium dichromate, and said silver complexing agent comprises 2-mercaptoimidazole.
 11. A process according to claim 7 wherein said groups capable of forming covalent bonds with silver consists of mercaptan groups.
 12. A process according to claim 7 wherein said silver complexing agent is 2-mercaptoimidazole.
 13. A process according to claim 7 wherein said silver complexing agent is compound which is soluble in water in a concentration of at least 10 5 moles/liter at 70* F. and wherein said compound is capable of forming a silver complex having a ratio of at least 1 silver ion to 1 silver complexing agent in a molar basis in the presence of excess silver ions as measured by potentiometric titration. 